Patients with refractory and relapse lymphoblastic leukemia had poor outcome even with marrow ablative conditioning mostly standard iv-Bu-Cy or Cy-TBI. In this study, we focus on a new treatment strategy with high-dose chemotherapy regimen consisting of fludaraibine+cytarabine+cyclophosphamide+etoposide followed by reduced intensity condiotning regimen consisting of fludarabine, busulfan and post-infusion cyclophophamide.